Spring 观察者模式 EventListener

本文主要是介绍Spring 观察者模式 EventListener，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

Step 1: Set up a Spring Boot project

Step 2: Create a custom event (plain java object). implementation with ApplicationEvent (marker class).

public class MyCustomEvent extends ApplicationEvent {private String message;public MyCustomEvent(Object source, String message) {super(source);this.message = message;}public String getMessage() {return message;}
}

Step 3: Create an event publisher (spring bean with method). use ApplicationEventPublisher or ApplicationContext.

@Service
public class MyEventPublisher {private final ApplicationEventPublisher eventPublisher;public MyEventPublisher(ApplicationEventPublisher eventPublisher) {this.eventPublisher = eventPublisher;}public void publishEvent(String message) {MyCustomEvent event = new MyCustomEvent(this, message);eventPublisher.publishEvent(event);}
}

Step 4: Create an event listener (spring bean). Annotate a method within this class with the @EventListener annotation, specifying the event type that the method should handle.

@Component
public class MyEventListener {@EventListenerpublic void handleCustomEvent(MyCustomEvent event) {System.out.println("Received custom event: " + event.getMessage());// Handle the event logic here}
}

Step 5: Test the event handling

@Component
public class DemoComponent implements InitializingBean {@Overridepublic void afterPropertiesSet() {// Publish the custom eventeventPublisher.publishEvent("Hello, world!");}
}

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